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The latest subway crime in which a woman was robbed and forced to take off her underwear is only compounding existing fear over what seems like an increasing number of assaults underground. Katy Tur reports. (Published Friday, Sept. 23, 2011)

A recent string of subway attacks in New York City, including the robbery and attempted rape of a woman on the F train Wednesday, are part of a citywide crime spike underground, according to officials.

Crime in the subways is up 16.6 percent over the same period last year, according to the NYPD.

Much of the rise in crime is being attributed to grand larcenies, but women who travel on the trains late at night or early in the morning say they are also concerned bout attacks.

"It's definitely less safe," said Emmaly Salazar, who rides the subway from her Brooklyn home late at night to get to work. "The F train is empty and I don't see any police around here."

Weird News Photos: Holiday Edition

Salazar's subway stop is Fort Hamilton Parkway, the site of a recent underground assault.

In that attack at about 2:25 a.m. Wednesday, a man cornered a woman on the F train at the station in Windsor Terrace, put his hand around her throat, brandished a knife and demanded her possessions.

He then forced her to take off her underwear and fled. Police Thursday released a surveillance video (below) and a sketch of the suspect (at right).

VIDEO: Surveillance of Suspect Wanted in Subway Attack

Police released surveillance video of a suspect wanted in an attack on the F train.

(Published Thursday, Sept. 22, 2011)

Also Wednesday, a woman in Brooklyn reported being followed by a man from the Prospect Avenue subway station, who then groped her in what's now being probed as the 11th sexual assault in the area since March.

Wednesday morning, police announced they were searching for a woman who had slashed two other young women in the face on the 4 train in the Bronx.

Clint Van Zandt, a former FBI profiler and NBC News crime analyst, believes some criminals are emboldened by others committing similar crimes and getting away with it.

"I think that you've probably got copycats out there, and I think this could continue," Van Zandt told NBC New York. "Law enforcement need to redouble their efforts and work as quickly as possible to make an arrest."

Police pointed out that while overall crime has risen, felony assaults were actually down 6.9 percent since this time last year.

And crime rates are nowhere near the levels of the 1980s, when violence was so rampant New Yorkers avoided using trains.

Editor's note: The video that runs at the top of this story says subway crime was up 16.9 percent. The correct figure is 16.6.